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SPC Mar 28, 2025 2000 UTC Day 1 Convective Outlook

4 months 4 weeks ago

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Fri Mar 28 2025 Valid 282000Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF SOUTHEASTERN TEXAS INTO WESTERN/CENTRAL LOUISIANA... ...SUMMARY... A severe storms threat will continue across coastal Texas into Louisiana this afternoon, with primary risks including a tornado or two and damaging wind. Isolated severe hail and wind is also possible this evening/tonight from Nebraska into portions of the Upper Midwest. ...20z Update... A Slight Risk was added across portions of far southeastern Texas into western/central Louisiana with this update. Through the morning/afternoon, supercell development has been ongoing with rotation observed on radar. The environment across this region is characterized by strong low-level shear, which is evident in enlarged low level hodographs on VAD profiles from LCH and POE. Daytime heating has led to MLCAPE around 500 J/kg across the region with dew points in the mid to upper 60s (some 70s along the coast). Additional thunderstorm development is expected through the afternoon as upper level forcing increases with a vort max currently upstream across southern Texas, with potential for more supercells and a tornado or two. Elsewhere, the Marginal Risk across Nebraska into the Upper Midwest remains unchanged. See previous discussion below for more information. ..Thornton/Smith.. 03/28/2025 .PREV DISCUSSION... /ISSUED 1122 AM CDT Fri Mar 28 2025/ ...Coastal Texas into Louisiana... Satellite imagery late this morning shows a mid-level trough over south-central TX into northeastern Mexico, and a vorticity max over the middle coastal plain of TX. Largely displaced from incipient outflow-generated air from a couple of western Gulf thunderstorm clusters, southeasterly low-level flow is advecting richer moisture into southeast TX/western LA. Cloud breaks will lead to some heating from the middle to upper coasts of TX into western LA. Surface dewpoints ranging from the upper 60s near the coast to the mid 60s as far north as I-20, will contribute to 250-1000 J/kg MLCAPE per model forecast soundings. Sufficiently enlarged low-level hodographs (0-1 km SRH 100-200 m2/s2) and a moist boundary layer and appreciable 0-3km CAPE, will support a conditional setup for several mini supercells. The main threats with this highly dependent mesoscale scenario would be a risk for a couple of tornadoes and localized damaging gusts. Uncertainty is rather high regarding this forecast due to low confidence in a few warm sector cells developing this afternoon. However, if isolated to scattered storms were to develop, the greatest potential severe threat would occur primarily in the 18-00 UTC period. This potential activity would likely diminish by early to mid evening owing to the loss of daytime heating. ...Nebraska into the Upper Midwest... Upper ridging will be gradually suppressed today as a low-amplitude shortwave trough moves eastward across the northern/central Plains and Upper Midwest through the period. Modest low-level moisture is forecast to continue streaming northward along/south of a sharpening warm front across MN/WI, and east of a cold front that will develop southward across parts of the northern/central Plains by this evening. Isolated to scattered thunderstorms may develop by mid to late evening along/near both fronts as low-level warm advection strengthens, from central NE northeastward into southern MN and central WI. Steep mid-level lapse rates will aid in the development of moderate MUCAPE, while deep-layer shear appears marginally supportive of organized convection. Any sustained thunderstorms could produce isolated severe hail and damaging winds. This activity will likely be elevated with eastward extent into the Upper Midwest through the evening and overnight, with a continued hail threat. Read more